Psalm 139:13–16 describes the formation of a child in terms of God's direct, hidden work: "thou hast covered me in my mother's womb... my substance was not hid from thee, when I was made in secret." The Hebrew word for "covered" — cakak — means to weave, to knit. The child with complications is still being formed by the same hands. The medical picture is not the full picture. God is at work in what doctors cannot see.
Isaiah 41:10 repeats its reassurance three times: "I will strengthen thee; yea, I will help thee; yea, I will uphold thee." The triple repetition is the kind used when fear is running faster than words can catch. God says it three times not for poetic effect but because the person he is speaking to needs to hear it more than once.
Commentary is from a charismatic Protestant perspective, drawing on KJV text and public-domain sources including Spurgeon, Andrew Murray, and Matthew Henry.